UNIVERSITY OF SOUTH AFRICA (UNISA)
College of Science, Engineering and Technology — School of Computing
⋄
HUMAN-COMPUTER INTERACTION
Assignment 04 — Semester 2, 2026
⋄
Module Code: INF1520
Module Name: Human-Computer Interaction
Assignment No.: Assignment 04
Tutorial Letter: INF1520/102/0/2026
Due Date: September 2026
Semester: Semester 2, 2026
Submitted in partial fulfilment of the requirements for Human-Computer Interaction (INF1520)
at the University of South Africa.
,UNISA | INF1520 Human-Computer Interaction — Assignment 04
Question 1: The Four Eras of Computing Devices and HCI
The development of computing devices and the practice of human-computer interaction
can be traced through four overlapping but distinct eras: the mainframe era, the personal
computing era, the internet era, and the mobile and ubiquitous computing era (Elliot and
Kraemer, 2008). Each era reflects a shift in who used computers, how many people shared a
single machine, and how directly a person could interact with it.
1.1 The Mainframe Era
In the mainframe era, one large, centralised computer was shared by many people, usually
through batch processing on punch cards or magnetic tape. There was no direct, real-time
interaction between the user and the machine: a program was submitted, queued, and the
results returned later by an operator. Interaction was mediated entirely by trained special-
ists, screens and keyboards for ordinary end users were largely absent, and the "interface"
consisted of command syntax rather than any visual representation of the system state.
1.2 The Personal Computing Era
The invention of the microprocessor made it possible for one computer to be used by one per-
son at a time. This era introduced the graphical user interface, pioneered at Xerox PARC and
popularised by Apple and Microsoft, along with the WIMP paradigm (windows, icons, menus,
pointer) and the desktop metaphor. Interaction became direct and visible: users could see the
objects they were manipulating and receive immediate feedback, which is the foundation of
what Shneiderman later formalised as direct manipulation.
1.3 The Internet Era
The rise of the World Wide Web connected previously isolated personal computers into a sin-
gle, navigable information space. Hyperlinks, browsers, e-mail, and later e-commerce shifted
the focus of HCI from a single application on a single machine to navigating, searching, and
communicating across a network of remote systems and other people. Interface concerns
expanded to include information architecture, findability, and trust between strangers trans-
acting online.
Page 1 of 16
, UNISA | INF1520 Human-Computer Interaction — Assignment 04
1.4 The Mobile and Ubiquitous Computing Era
Weiser (1991) described ubiquitous computing as the "third wave" of computing, following
the mainframe (many people, one computer) and the personal computer (one person, one
computer), in which a single person now uses many computers embedded, worn, or carried
throughout their environment. Smartphones, tablets, and wearables introduced touch, ges-
ture, and voice as primary input modalities, made context-awareness and location a design
concern, and pushed computing off the desktop and into everyday objects and activities.
1950s–1960s 1970s–1980s 1990s–2000s 2000s–present
Mainframe Era: Personal Computing Internet Era: net- Mobile & Ubiquitous
many users, one Era: one user, worked machines, Era: one user, many
shared machine, one machine, the Web, e-mail, embedded devices
batch processing GUI and WIMP e-commerce
Figure 1: The four eras of computing devices and HCI (adapted from Elliot and Kraemer, 2008;
Weiser, 1991)
Page 2 of 16
College of Science, Engineering and Technology — School of Computing
⋄
HUMAN-COMPUTER INTERACTION
Assignment 04 — Semester 2, 2026
⋄
Module Code: INF1520
Module Name: Human-Computer Interaction
Assignment No.: Assignment 04
Tutorial Letter: INF1520/102/0/2026
Due Date: September 2026
Semester: Semester 2, 2026
Submitted in partial fulfilment of the requirements for Human-Computer Interaction (INF1520)
at the University of South Africa.
,UNISA | INF1520 Human-Computer Interaction — Assignment 04
Question 1: The Four Eras of Computing Devices and HCI
The development of computing devices and the practice of human-computer interaction
can be traced through four overlapping but distinct eras: the mainframe era, the personal
computing era, the internet era, and the mobile and ubiquitous computing era (Elliot and
Kraemer, 2008). Each era reflects a shift in who used computers, how many people shared a
single machine, and how directly a person could interact with it.
1.1 The Mainframe Era
In the mainframe era, one large, centralised computer was shared by many people, usually
through batch processing on punch cards or magnetic tape. There was no direct, real-time
interaction between the user and the machine: a program was submitted, queued, and the
results returned later by an operator. Interaction was mediated entirely by trained special-
ists, screens and keyboards for ordinary end users were largely absent, and the "interface"
consisted of command syntax rather than any visual representation of the system state.
1.2 The Personal Computing Era
The invention of the microprocessor made it possible for one computer to be used by one per-
son at a time. This era introduced the graphical user interface, pioneered at Xerox PARC and
popularised by Apple and Microsoft, along with the WIMP paradigm (windows, icons, menus,
pointer) and the desktop metaphor. Interaction became direct and visible: users could see the
objects they were manipulating and receive immediate feedback, which is the foundation of
what Shneiderman later formalised as direct manipulation.
1.3 The Internet Era
The rise of the World Wide Web connected previously isolated personal computers into a sin-
gle, navigable information space. Hyperlinks, browsers, e-mail, and later e-commerce shifted
the focus of HCI from a single application on a single machine to navigating, searching, and
communicating across a network of remote systems and other people. Interface concerns
expanded to include information architecture, findability, and trust between strangers trans-
acting online.
Page 1 of 16
, UNISA | INF1520 Human-Computer Interaction — Assignment 04
1.4 The Mobile and Ubiquitous Computing Era
Weiser (1991) described ubiquitous computing as the "third wave" of computing, following
the mainframe (many people, one computer) and the personal computer (one person, one
computer), in which a single person now uses many computers embedded, worn, or carried
throughout their environment. Smartphones, tablets, and wearables introduced touch, ges-
ture, and voice as primary input modalities, made context-awareness and location a design
concern, and pushed computing off the desktop and into everyday objects and activities.
1950s–1960s 1970s–1980s 1990s–2000s 2000s–present
Mainframe Era: Personal Computing Internet Era: net- Mobile & Ubiquitous
many users, one Era: one user, worked machines, Era: one user, many
shared machine, one machine, the Web, e-mail, embedded devices
batch processing GUI and WIMP e-commerce
Figure 1: The four eras of computing devices and HCI (adapted from Elliot and Kraemer, 2008;
Weiser, 1991)
Page 2 of 16
